Loop

Overview

The Loop operation runs the actions in Do once for every element of Items, for example for every row of a CSV file or every entry of an API response.

Items	Iterations	item
a number, e.g. 5	5	{{item.value}} = 1 … 5
Range(10,15)	6	{{item.value}} = 10 … 15
a JSON list, e.g. ["a","b"] or {{Query.Response.Body.items}}	per element	objects stay objects ({{item.id}}), simple values are in {{item.value}}
path of a .json file with a list	per element	as above
path of a .csv file or CSV text over several lines	per row	{{item.<column name>}}
anything else	1	{{item.value}} = the text

Comma-separated enumeration

A one-line enumeration like a,b,c is not a list but a single element. Write lists as JSON: ["a","b","c"].

CSV: the separator is ; if the first line contains one, otherwise ,. The first line is the header, unless one of its cells is a whole number; without a header the columns are named col0, col1, … Quoted values containing the separator are not supported.

In the diagram of the workflow editor Loop has a form: Items (Items, values as above; inside, {{item}} and {{index}} apply), At most rounds, Stop after errors and Pause between rounds (ms). Drag values in from the test view.

Structure

{
  "Type": "Loop",
  "Name": "WriteEachCustomer",
  "Parameters": {
    "Items": "C:\\RUNOS\\Data\\customers.csv",
    "Do": [ { "Type": "SMTP", "Name": "Write", "Parameters": { … } } ],
    "MaxLoopCount": 100,
    "BreakOnErrors": 3,
    "DelayMs": 1000
  }
}

Parameter	Default	Meaning
Items	–	What to iterate, see above
Do	–	Actions per iteration
MaxLoopCount	all	At most this many iterations
BreakOnErrors	unlimited	Stop after this many failed iterations; the loop then ends as failed
DelayMs	–	Pause after each iteration in milliseconds

Placeholder in the iteration	Content
{{item}}	the current element (always an object)
{{item.value}}	the value for simple elements
{{index}}	position, starting at 0
{{count}}	number of all elements

The result of an action in Do is stored under its name and overwritten in every iteration; after the loop it holds the last iteration. Nested loops share item, index and count: inside the inner loop they refer to its element, after the inner loop again to the outer one’s. Two loops running at the same time in two branches of a Parallel each have their own item.

Result

"Response": {
  "Results": [ { … result of every action of every iteration … } ],
  "ExecutedCount": 12,
  "ErrorCount": 0,
  "StopReason": "Completed"
}

StopReason is Completed, BreakOnErrors or StopWorkflow (a StopWorkflow action in Do ended the loop and the run).

If an action in Do fails, the remaining actions of that iteration are skipped, and the error is recorded with the element’s number in Status.Errors and ErrorCount. The loop continues with the next element until BreakOnErrors is reached. A run with errors in single iterations shows red in the workflow list.

Example

customers.csv:

Name;Email;CustomerNo
Muster GmbH;info@muster.de;1001
Beispiel AG;post@beispiel.de;1002

{
  "Type": "Loop",
  "Name": "WriteEachCustomer",
  "Parameters": {
    "Items": "C:\\RUNOS\\Data\\customers.csv",
    "DelayMs": 1000,
    "BreakOnErrors": 3,
    "Do": [
      {
        "Type": "SMTP",
        "Name": "Write",
        "Parameters": {
          "SmtpServer": "smtp.example.com",
          "SmtpUser": "{{connector.Mailserver.Username}}",
          "SmtpPassword": "{{connector.Mailserver.Password}}",
          "From": "service@example.com",
          "To": "{{item.Email}}",
          "Subject": "Your customer number {{item.CustomerNo}}",
          "Body": "Hello {{item.Name}},\n\nyour customer number is {{item.CustomerNo}}."
        }
      }
    ]
  }
}